According to the new Chinese rhyme, at present one or two are flat tones and three or four are flat tones. But according to the ancient rhyme, for example, "wet" is the first sound in our Mandarin, but it is ambiguous in the ancient rhyme. For another example, "Guo" is the second sound in our pronunciation, which is flat, but it is awkward in ancient rhyme. There are currently three types:
The first one, which is often used in metrical poems, is flat and even rhyme.
The second is the word Lin, which is commonly used in lyrics.
The third is the new rhyme of Chinese, which is divided according to Putonghua, and the rhyme characters are universal.